Im in the process of doing an overhaul on my cooling system and I have a few questions. I am draining all of the coolant out of my Koyo radiator right now, but I'm not sure how to get the rest of the old coolant out of the block. Im trying to get this thing bone dry so I can run mostly water, because of the 100+ degree weather out. My water pump is good so theres no need to replace that, but I'm doing my t-stat. Also my radiator cap is a bit on the old side, so I would like to change that aswell. The only problem with this is when I searched I could not get a straight answer on weather to use a 13 or 16psi cap. Mine has some japanese writing on it and a .9 so I think thats 13 but I'm not sure. Any cooling experts out there?

 

On the driver side of the block theres a 14mm brass thing stickout of from the engine mount. This is the drain plug for the block.

 

Right under the oil filter? Any idea on the radiator cap psi?

 

13psi.

its under the oil FILLER tube at the bottom of the center iron inside of the driver side engine mount.

 

can we use the 16 psi cap? will it aid in cooling? especially if we are running mostly water? higher bp and all that.

 

A higher Cap rating will prevent the Engine's Cooling system from "purging" when it is overheating..so If the Cap doesn't Let the Pressure out,it will another way,In the form of Blowing a Coolant seal....Draining: I get Lazy,I just Pop a Lower rad hose and Let it Run out..replace..Throw some water in,run a minute and Pop it again..Then Fill with appropriate coolant.

 

Mazdaspeed says up to 17-18 PSI is ok, but don't go over that.

 

Running mostly water will just cause your engine to overheat faster. A 50/50 mixture gives the best protection..... hot or cold.

 

False!

 

water has better cooling properties than coolant.

 

Thats what I've been told.

 

2.5 times better.

 

DAMN!! now I have another annoying problem. I broke one of the studs off at the t-stat neck. I guess I have to drill and tap it out. ******* old *** bolts!

 

Protection from corrosion yes, but water is a better heat exchanger than Ethylene glycol.

 

if you run disstilled water then should be ok.. i never ran all water, but my mixes usually are mostly water

 

Got a Link to that?

 

isint it the minerals in the water that makes it bad like tap water . but acouple cheap gallons from the supermarket shuold be okay?

 

No... you have to be a Mazda Motorsports member to get to that info, although it might be in the mazdaspeed catalog that you can access even if you're not a member.